Lapping machine



May 22, 1945. w, F. EGGER LAPPING MACHINE Fi led Nov. 11, 1943 2Sheets-Sheet 1 INVENTOR. WALTE R EEG GER ATTORNEYS May 22, 1945. w. F.EGGER LAPPING MACHINE 2 Sheets-Sheet 2 Filed Nov. 11, 1943 V G 9 M m n AB 2 M M Patented May 22, 1945 LAPPIN G MACHINE Walter F. Egger, RockyRiver, Ohio, assignor to Albert P. Schraner, Shaker Heights, Ohio, doingbusiness as A. P. Schraner & Co.

Application November 11, 1943, Serial No. 509,850

12 Claims.

This invention relates as indicated to lapping machines and moreespecially to machines of the character whichare designed to lap orpolish the cylindrical surfaces of rotatable workpieces such ascrankshafts and the like, i. e. those portions of the crankshaft onwhich the main and connecting rod bearing surfaces are provided.

It is a more specific object of my invention to provide an apparatus ofthe character described which will effectively lap or polish thoseportions of said bearing surfaces which extend at right angles to theaxis of the workpiece, that is, they extend in a plane substantially.normal to the axis about which the shaft is rotated.

Lapping machines of this character generally employ an abrasive coatedribbon, an intermediate portion of which is moved into engagement withthe area being operated upon.

It is a further and more specific object of my larly pointed out in'theclaims, the following de-- scription and the'annexed drawings settingforth in detail certain illustrative embodiments ofthe invention, thesebeing indicative, howevenof but.

a few of the various ways in which the principle of the inventionmaybeemployed.

In said annexed drawings: Fig. 1 is a side elevational view partially insectionof one form of apparatus embodyingv the principles of myinvention;

Fig. 2 is a side elevational view drawn to an enlarged scale of aportion ofthe apparatus illustrated in Fig. 1; m

- Fig. 3 is a plan view of that portion of the apparatus illustrated inFig. "2;

Fig.4 is a transverse sectional view of the apparatus illustrated inFig. Ltaken on a plane substantially indicated by the line 4-4;

Figs. 5 and 6 are respectively fragmentary sectional views of a portionof the apparatus as illustrated in Fig. 5 showing the several partsthereof in dilferent positions,

i Fig. 7 is aside elevational view of another form of apparatusembodying in a different environment'one of the principles of myinvention;

Fig. 8 is a fragmentary side elevational view of one of thework-engaging jaws of the apparatus of Fig. 7; and

Fig. 9 is a transverse sectional view of the structure illustrated inFig. 8, taken on a plane substantially indicated by the line 9-9.

Referring now more specifically to the drawings and more especially toFig. 1, the apparatus here illustrated, and incorporating certain of thefeatures of my invention, is part only of a complete lapping machinesuch as that illustrated in my prior Patent No. 2,121,025, issued Jan.21, 1938. Only so much of that machine as is related to the presentinvention has been illustrated and will be described herein. For adescription of the general operation of the machine, reference may behad to my said prior patent.

In my said prior patent the bearing surfaces of the crankshaft areengaged at diametric opposite points by jaws over which are stretched.ribbons of abrasive coated material, and such'jaws are urged intoengagement with the outer cylindrical surface of the bearing areas underthe influence of a fluid actuated ram l. The present invention isconcerned with the provision of workengaging heads which will lap orpolish the shoulders or side parts of the bearing areas, i. e.

those which extend in a plane normal to the axis of rotation of thecrankshaft. Two identical heads are provided, each carried on the lowerend of bell-crank levers 2, the upper ends of which levers are connectedthrough toggle links 3 to the head 4 of the piston rod 5 of the jack I.Thus, when the piston rod is elevated, the toggle linkage just describedwill move the heads, generally indicated at 6, into engagement with thecrankshaft, and when the piston rod 5 descends, the head 6 will be movedout of engagement with the crankshaft. The construction of the heads 6is most clearly illustrated in Figs. ,2 to 6. Since these heads areidentical, only one will be described, and similar reference characterswill be employed to designate corresponding parts on the other head.

To a base member 'I there is secured, as by welding or otherwise, anupstanding member 8, and also a pin 9. Rotatably mounted on the pin 9 isa spool ID, carrying an abrasive coated ribbon ii. The upstanding member8 is provided with slots l2 at opposite sides for the purpose of guidingthe abrasive coated ribbon which is passed therethrough. V V v 7Likewise secured to the base 1 is an upstanding wedge-shaped part l3,the uniform cross-section of which is most clearly apparent from aninspection of Figs. 4 to 6. The member i3 is provided with a slot on itsouter vertical face into which extends the lower end of the bell-crank2. Aligned openings extending transversely,

through the member I3 and the end of the arm 2 receive a pin I4 by whichthe member I3 is removably attached to the arm 2.

Mounted on opposite sides of the member l3 are cam members l5 and IS,the uniform crosssection of which will be apparent from Figs. 4 and 6,and the lateral configuration of which will be apparent from Fig. 2. Theinner faces of the members l5 and I6 are arcuate and of a diameterslightly greater than the diameter of thebear ing surface on which theapparatus is designed to operate. I

The upper and lower corners of each of members l5 and iii are providedwith identical removable projections l'l, each of which is provided withan opening [8 to receive the terminal portion of a cross-shaft l9. Onthe cross-shafts l9 are mounted rollers 20, the 'outer surfaces of whichlie on an are having a diameter slightly less than the arc of the innerfaces of the members l5 and l'6., The are on which the rollers 20 lieshould have .a radius equal to the radius of the bearing surface beingoperated upon. The shafts I!) are securedatone end in either the member,[5 or IE, andat their opposite ends slidable in the opening embracingthe same, so that the members and I6 may move toward and away from eachother.

On the upper and lower faces of each of members I5 and l6 are projectingpins 2I, and to such pins are secured the opposite ends of springs 22biased so as to resiliently urge the members 15 and I6 toward eachother; against the. inclined opposedfacesof the central member l3.

The members [5 and [6 are provided with slots 23, the vertical dimensionof which is equal to the, diameter of thepinl l, with'the horizontaldimension substantially greaterthan such diameter in orderthat, asviewed in Figs. 4 to 6, relative movement betweenthe members [5 and I6and central'member lfimay occur.

Intermediately or their ends, the members l5 and l ar provid d ith attaced pads 24 of oil -resistant synthetic rubber. The inner face ofthe pads24, i. e those faces directed toward the cylindrical bearing surface,have a radius sufficiently greater than the radius of such bean ingsurfaces sothat the abrasiv coated ribbon passing thereover will nothave contact with such cylindrical surfaces when the rollers are inengagement with such cylindrical surfaces.

The function and operation of the apparatus just illustrated is brieflyas follows:

With the heads mounted on the ends of the arms 2 and out-ofengagementwith the bearin surface on the crankshaft, the piston rod 5 is elevatedcausing suchheads through the toggle linkage-,prgeviously described, tomove ,into engagement with the bearing surface. With the heads out ofengagement with the bearing surface, the springs ;22, urging the membersl5 and I6 toward "each Qther, will cause such members and associatedpart'l3 to occupythe relationship illustrated in Fig. 5. 'I-Io wever,when the toggle arm's'Z are'mov'ed toward thebearing, they, actingthrough the wedge-shaped members I3, will cause the membersli'and ffi tospread apart, as illustrated in Fig. 6, until their opposite faces, 1.e., those carrying the pads 24, m v i o enra ement with the radial samans 25 on opposite sides of the cylindrical bearia jeieastamens.

The pads 24 will hold the abrasive coated ribbon against these radialshoulders, and during the subsequent rotation of the crankshaft, suchradial shoulders, as well as the fillet joining the radial shoulders andthe cylindrical surface, will be lapped and polished.

At the conclusion of the operation, the piston rod 5 will be lowered,separating the heads from the shaft, whereupon the springs will move themembers l5 and I6 toward each other, and the apparatusmay then be swungout of engagement with the crankshaft.

In any lapping operation, such as that just described, and such as isadapted to be performed by the apparatus of my aforementioned priorpatent, some means must be provided for the purpose ofpreventingshifting between the abrasive coated ribbon and the lapping arm or headby which the same is moved into engagement with the work.

It has been common practice up to the time of my invention to coat themachine part which engages the back face of the abrasive ribbon with arelative coarse abrasive material so as to prevent relative movementbetween the ribbon and the part which forces the ribbon into engagementwith the work. Heretofore, no other means has been found satisfactoryfor this purpose. In practice, however, these abrasive coated ribbonshave a tendency to tear or become misaligned, and when this happens thepart carrying the coarse abrasive comes in contact with the bearingsurface to be lapped, scoring, and in many times, ruining the entirecrankshaft.

The employmentof oil-resistant synthetic rubber as the material for thepad 24 obviates this difficulty, I have found that commerciallyavailable synthetic rubber, sold under the name Neoprene, and otherproducts similar thereto, is entirely satisfactory for this purpose.

- This expedientof holding in place and resiliently backing up theabrasive coated ribbon may be employed in environments other than thespecific embodiment of my invention thus far described.

For example, in an apparatus of the character illustratedin my saidprior patent, and as illustrated in Fig. 7, the invention will I, befound of particular utility. In this type' of lapping machine, thecylindrical surfaces of the bearing to be lapped are engaged atdiametrically opposite areas by means of jaws 21, the inner faces ofwhich are arcuate on a radius substantially equal to the radius of thecylindrical bearing surface i la'pbed.

In 'accordanc'e' with th rior practice, it has been conventional toprovide on'these inner faces of the blocks 21 a shee'tf'of coarse sandpaper holding the abrasive coated ribbon :28 from slipping relatively tothe blocks 21 during the lapping operation. as previously indicated,should the abrasive coated ribbon 28;tear, then-the coarse sand papercol'nes'in contact with the-bearing surface, many times so-scoring thesame as to require rejection of the entire crankshaft.

This problem I have solved by providing on=the inner faces of the blocks-21 a layer 29 of synthetic rubber, and inthe preferred embodiment of myinvention, the-resilient pad-thus provided has a series of spacedgrooves 30 formed'therein, such grooves extending substantially parallel-to the axis of relativ rgtation -bet ween'the-bearing and the blocks21. This expedient of grooving the rubber pad-is of particularimportance in th'a't'it permits'intermediate spaced portions of,

the ribbon 28 to become wedged in the grooves, thus insuring againstrelative movement between theribbon and the padduring the lappingopera--- tion.

Similarly, if'the extent of the pads 24 of Fig. 2

are considerable, then they too should preferably be provided withgrooves which extend transversely of the direction of relative movementbetween the part being lapped and the abrasive coated ribbon.

I have thus provided an improved lappingmachine which'accomplishes allof the objects aforesaid, and which in particular is effective to polishor lap those surfacesof crankshafts which have heretofore been finishedentirely by hand.- v

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed. 1

I therefore particularly point out and distinctly claim as my invention:

1. In apparatus for lapping a work piece of the general form of a; crankshaft with crank-pin and adjoining shoulder surfaces, th combination ofa carrier part, primary means on said carrier partjengageable with thework in an area adjacent said shoulder surface, secondary means on saidcarrier engageable with said shoulder surface and movable relatively tosaid carrier in a direction substantially parallel to the axis of thecrank-pin, and means for effecting said last named movement.

2. In apparatus for lapping a work piece of the general form of a crankshaft with crank-pin and adjoining shoulder surfaces, the combination ofa carrier part, primary means on said carrier part engageable with thework in an area adjacent said shoulder surface, secondary means on saidcarrier engageable with said shoulder surfaces and movable relatively tosaid carrier in a direction substantially parallel to the axis of thecrank-pin, means intermediately of said primary and secondary meanswhereby pressure of the former against said work effects said last namedmovement.

3. In apparatus for lapping a work piece of the general form of acrank-shaft with crank-pin and adjoining shoulder surfaces, thecombination of a carrier part, primary means on said carrier partengageable with the work in an area adjacent said shoulder surface andresponsive to such engagement movable relatively to said carrier in aplane substantially normal to the axis of the crank-pin, secondary meanson said carrier engageable with said shoulder surface and movablerelatively to said carrier in a direction substantially parallel to theaxis of the crank-pin, means intermediately of said primary andsecondary means whereby relative movement between the former and saidcarrier effects relative movement between said secondary means and saidcarrier to cause said secondary means to move into engagement with saidshoulder surfaces.

4. In apparatus for lapping a work piece of the general form of acrank-shaft with crank-pin and adjoining shoulder surfaces, thecombination of a carrier part, primary means on said carrier partengageable with-the work in an area adjacent said shoulder surface andresponsive to such engagement movable relatively to said carrier in aplane substantially normal to the axis of the crank-pin, secondary meanson said carrier engageable with said shoulder surface and movablerelatively to said carrier in a direction substantially parallelto theaxis of the crank-pin, means intermediately of said primary andsecondary means whereby relative movement between the former and saidcarrier effects relative movement between said secondary means and saidcarrier to cause said secondary means to move into engagement with saidshoulder surface, and work engaging pads of resilient material on thosefaces of said secondary means which are opposed to said shouldersurfaces, said pads provided with grooves extending across the facethereof in a direction substantially parallel to the axis of thecrank-pin,

5. In apparatus for lapping spaced opposed shoulder surfaces on arotatable work piece of the general form of shoulder surfaces adjacent acrank-piece, the combination of a carrier part, primary means on saidcarrier part engageable with th work in an area intermediately of saidshoulder surfaces, secondary means on said carrier engageable with saidshoulder surfaces and movable relatively to said carrier in a directionsubstantially parallel to the axis of the crank-pin, and means foreffecting said last named movement. i

6. In apparatus for lapping spaced opposed shoulder surfaces on arotatable work piece of the general form of shoulder surfaces adjacentacrank-piece, the combination of a carrier part, primary means on saidcarrier part engageable with the work in an area intermediately of saidshoulder surfaces, secondary means on said carrier engageable with saidshoulder surfaces and movable relatively to said carrier in a directionsubstantially parallel to the axis of the crank-pin,

means intermediately of said primary and secondary means wherebypressure of the former against said work effects said last namedmovement. 7

'7. In apparatus for lapping spaced opposed shoulder surfaces on arotatable work piece of the general form of shoulder surfaces adjacent acrank piece, the combination of a carrier part, primary means on saidcarrier part engageable with the work in an area intermediately of saidshoulder surfaces and responsive to such engagement movable relativelyto said carrier in a plane substantially normal to the axis of thecrankpin, secondary means on said carrier engageable with said shouldersurfaces and movable relatively to said carrier in a directionsubstantially parallel to the axis of the crank-pin, meansintermediately of said primary and secondary means whereby relativemovement between the former and said carrier effects relative movementbetween said secondary means and said carrier to cause said secondarymeans to move into engagement with said shoulder surfaces.

8. In apparatus for lapping spaced opposed shoulder surfaces on arotatable work piece of the general form of shoulder surfaces adjacent acrank-piece, the combination of a carrier part, primary means on saidcarrier part engageable with the work in an area intermediately of saidshoulder surfaces and responsive to such engagement movable relativelyto said carrier in a plane substantially normal to the axis of thecrankpin, secondary means on said carrier engageable with said shouldersurfaces and movable relatively to said carrier in a directionsubstantially parallel to the axis of the crank-pin, meansintermediately of said primary and secondary means whereby relativemovement between the former and said carrier eifects relative movementbetween said secondary means and said carrier to cause said secondarymeans to move into engage-merit with said shoulder surfaces, and workenga ing pads of resilient material on those faces of said secondarymeans which are opposed to said shoulder surfaces. v

9. In apparatus for lapping spaced opposed shoulder surfaces on arotatable work piece of the general form of shoulder surfaces adjacent acrank-piece, the combination of a. carrier part, primary means on saidcarrier part engageable with the work in an area intermediately of saidshoulder surfaces and responsive to such engagement movable relativelyto said carrier in a plane substantially normal to the axis of thecrankpin, secondary means on said carrier engageable with said shouldersurfaces and movable relatively to said carrier in a directionsubstantially parallel to the axis of the crank-pin, meansintermediatelv of said primary and secondary means whereby relativemovement between the former and said carrier effects relative movementbetween said secondary means and said carrier to cause said secondarymeans to move into engagement with said shoulder. surfaces, and workengaging pads of resilient material on those faces of said secondarymeans which are opposed to said shoulder surfaces, said pads providedwith grooves extending across the face thereof in a directionsubstantially parallel to the axis of the crank-pin.

ed ribbon into engagement with a substantially I cylindrical surface ona rotating work piece, of

a pad of oil-resistant synthetic rubber substituteon said pillowarranged to engage the back face of ribbon, said pad provided withgrooves extending across the ribbon-engaging face thereof in a directionangularly related to the plane of relative rotation between said pillowand the work iece.

12. In apparatus for lapping a work piece of general form of acrank-shaft with crank-pin and adjoining shoulder surfaces, an arcuatepillow adapted to maintain an intermediate portion of an abrasive ribbonin engagement with a crank-pin surface, and small rollers mounted on theupper and lower corners thereof, the are on which the rollers lie havinga radius substantially equal to the radius of the crank-shaft.

WALTER F. EGGER.

